Ensemble initial perturbations around Typhoon Sinlaku (2008) produced by ECMWF, NCEP, and the Japan Meteorological Agency (JMA) ensembles are compared using The Observing System Research and Predictability Experiment (THORPEX) Interactive Grand Global Ensemble (TIGGE) data, and the dynamical mechanisms of perturbation growth associated with the tropical cyclone (TC) motion are investigated for ...

The new radiation-transfer scheme RRTM is described in the article on page 2.The new scheme includes the representation of sixteen spectral bands, compared with six bands in the previous operational scheme.This allows improvements in the spectral description of the radiative properties of both the earth’s surface and the clouds.Tests of the impact of the scheme indicate improved anomaly correla...

In this study, we evaluate the ability of the BRAMS (Brazilian Regional Atmospheric Modeling System) mesoscale model compared to ECMWF global analysis to simulate the observed vertical variations of water vapour in the tropical upper troposphere and lower stratosphere (UTLS). The observations are balloon-borne measurements of water vapour mixing ratio and temperature from microSDLA (Tunable Dio...

At the European Centre for Medium-Range Weather Forecasts (ECMWF), scatterometer data from the ERS 1/2 platforms have been successfully assimilated between January 1996 up to an ERS-2 on-board failure in January 2001. This surface vector wind product over the global oceans had proven to give a positive impact on the ECMWF forecast skill in general, and the analysis of tropical cyclones in speci...

Oceanic surface pressure fields are derived from the NASA Quick Scatterometer (QuikSCAT) surface wind vector measurements using a two-layer similarity planetary boundary layer model in the midlatitudes and a mixed layer planetary boundary layer model in the tropics. These swath-based surface pressure fields are evaluated using the following three methods: 1) a comparison of bulk pressure gradie...

The performance of single models and ensemble prediction systems has been investigated with respect to quantitative precipitation forecasts. Evaluation is based on the potential economic value of +72 h/+96 h forecasts. The verification procedure consists of taking into account all precipitation amounts that are predicted in the vicinity of an observation in order to compute spatial, multi-event...

Despite its fundamental importance in radiative transfer, atmospheric dynamics and the hydrological cycle, atmospheric water is inadequately characterized particularly at a global scale. Occultation measurements from the Global Positioning System (GPS) should imporve upon thids situation. Individual occultations yield profiles of specific humidity accurate to -0.2 gkg providing sensitive measur...

This note has been prepared by the Physical Aspects Section of the Research Department at ECMWF. ECMWF is an operational centre for medium range weather forecasting, monthly forecasting, seasonal forecasting and ocean wave forecasting. The operational system is also used for re-analysis projects (ERA-15, ERA-40 and ERA-Interim). ECMWF operates a state of the art global atmospheric model with an...

Cloud and boundary layer variables from the European Centre for MediumRange Weather Forecasts (ECMWF) forecast model were compared with measurements made from surface instruments and from upward looking 8 mm wavelength radar and lidar at the Surface Heat Budget of the Arctic Ocean (SHEBA) ice camp during November and December of 1997. The precipitation accumulation, near-surface winds, and surf...

2. COMPARISON BETWEEN THE ECMWF 3DVAR AND 4DVAR SYSTEMS The ECMWF 4dVar system is, from the technical point of view, very similar to the 3dVar system. Both systems use the same unix scripts, and share much of the Fortran code. The same background error covariance matrix and observation operators are used, and most of the peripheral tasks such as fetching and archiving of fields and observations...